Human Respiratory Monitoring Based on Schottky Resistance Humidity Sensors

Two types of Schottky structure sensors (silicon nanowire (SiNW)/ZnO/reduced graphene oxide (rGO) and SiNW/TiO2/rGO) were designed, their humidity resistance characteristics were studied, and the sensors were applied to detect sleep apnea through breath humidity monitoring. The results show that the resistance of the sensors exhibited significant changes with increasing humidity, the response times of the two sensors within the relative humidity range of 23–97% were 49 s and 67 s, and the recovery times were 24 s and 43 s, respectively. Meanwhile, continuous breathing monitoring results indicate that the sensitivity of the sensors remained basically unchanged during 10 min of normal breathing and simulated apnea. The response of the sensor is still good after 30 days of use. We believe that the Schottky structure composite sensor is a very promising technology for human breathing monitoring.

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Evaluation Humidity Sensing Properties of Graphene/HS-TiO2 Nanocomposites

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19446 ◽

2021 ◽

Vol 21 (10) ◽

pp. 5143-5149

Author(s):

Zhen Zhu ◽

Wang-De Lin

Keyword(s):

Room Temperature ◽

Response Times ◽

Sol Gel ◽

Hollow Spheres ◽

High Sensitivity ◽

Humidity Sensing ◽

X Ray ◽

Transmission Electron ◽

Recovery Times ◽

Relative Humidity Range

This paper reports on a nanocomposite synthesized by sol–gel procedure comprising graphene sheets with hollow spheres of titanium dioxide (G/HS-TiO2) with varying weight percentages of graphene for the purpose of humidity sensors. The surface morphology of the nanocomposite was characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The structural properties were examined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The response to 12–80% RH at room temperature exhibited sensitivity (S = 135). However, the relative humidity range of 12–90% at room temperature exhibited higher sensitivity (S = 557). Sensors fabricated using the proposed nanocomposite exhibited high sensitivity to humidity, high stability, rapid response times, and rapid recovery times with hysteresis error of less than 1.79%. These results demonstrate the outstanding potential of his material for the monitoring of atmospheric humidity. This study also sought to elucidate the mechanisms underlying humidity sensing performance.

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Characterization and Humidity Sensing Application of ZnO-TiO2 Nanocomposite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.304.48 ◽

2011 ◽

Vol 304 ◽

pp. 48-52 ◽

Cited By ~ 2

Author(s):

Narendra Kumar Pandey ◽

Karunesh Tiwari ◽

Akash Roy

Keyword(s):

Relative Humidity ◽

Electronic Conduction ◽

Nanocomposite Powder ◽

Sensing Element ◽

Reaction Route ◽

Humidity Sensing ◽

Humidity Resistance ◽

Sem Micrograph ◽

Relative Humidity Range ◽

Humidity Range

Paper reports morphological and relative humidity sensing studies of ZnO-TiO2nanocomposite powder pellets obtained through solid-state reaction route. When exposed to humidity, resistance of pellets decreases with increase in relative humidity from 10-90%. Sensing element with 15 weight % of TiO2in ZnO shows best results with maximum sensitivity of 9.08 MΩ/%RH in 10-90% relative humidity range. This sensing element manifests smallest crystallite size of 71 nm as measured from XRD and lowest grain size of 207 nm calculated from SEM micrograph. This sensing element has the lowest value of activation energy, and hence higher electronic conduction.

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Preparation of Powders Containing Sb, Ni, and O for the Design of a Novel CO and C3H8 Sensor

Applied Sciences ◽

10.3390/app11209536 ◽

2021 ◽

Vol 11 (20) ◽

pp. 9536

Author(s):

Jorge Alberto Ramírez-Ortega ◽

José Trinidad Guillén-Bonilla ◽

Alex Guillén-Bonilla ◽

Verónica María Rodríguez-Betancourtt ◽

Lorenzo Gildo-Ortiz ◽

...

Keyword(s):

Response Times ◽

High Capacity ◽

Dynamic Tests ◽

X Ray Diffraction ◽

Wet Chemistry ◽

Good Thermal Stability ◽

Great Performance ◽

Vis Spectroscopy ◽

Recovery Times ◽

Response And Recovery

In this work, powders of NiSb2O6 were synthesized using a simple and economical microwave-assisted wet chemistry method, and calcined at 700, 800, and 900 °C. It was identified through X-ray diffraction that the oxide is a nanomaterial with a trirutile-type structure and space group P42/mnm (136). UV–Vis spectroscopy measurements showed that the bandgap values were at ~3.10, ~3.14, and ~3.23 eV at 700, 800, and 900 °C, respectively. Using scanning electron microscopy (SEM), irregularly shaped polyhedral microstructures with a size of ~154.78 nm were observed on the entire material’s surface. The particle size was estimated to average ~92.30 nm at the calcination temperature of 900 °C. Sensing tests in static atmospheres containing 300 ppm of CO at 300 °C showed a maximum sensitivity of ~72.67. On the other hand, in dynamic atmospheres at different CO flows and at an operating temperature of 200 °C, changes with time in electrical resistance were recorded, showing a high response, stability, and repeatability, and good sensor efficiency during several operation cycles. The response times were ~2.77 and ~2.10 min to 150 and 200 cm3/min of CO, respectively. Dynamic tests in propane (C3H8) atmospheres revealed that the material improved its response in alternating current signals at two different frequencies (0.1 and 1 kHz). It was also observed that at 360 °C, the ability to detect propane flows increased considerably. As in the case of CO, NiSb2O6’s response in propane atmospheres showed very good thermal stability, efficiency, a high capacity to detect C3H8, and short response and recovery times at both frequencies. Considering the great performance in propane flows, a sensor prototype was developed that modulates the electrical signals at 360 °C, verifying the excellent functionality of NiSb2O6.

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Sorption of water vapour by M-montmorillonite (M = Na, Li, La)

Clay Minerals ◽

10.1180/claymin.1990.025.4.07 ◽

1990 ◽

Vol 25 (4) ◽

pp. 485-498 ◽

Cited By ~ 13

Author(s):

J. M. Trillo ◽

J. Poyato ◽

M. M. Tobías ◽

M. A. Castro

Keyword(s):

External Surface ◽

Interlamellar Spacing ◽

Molecular Water ◽

Water Molecules ◽

Sorbed Water ◽

Octahedral Sites ◽

Interlamellar Water ◽

Relative Humidity Range ◽

Humidity Range ◽

Water Sorption Capacity

AbstractThe effect of heating on the water sorption capacity of a La-saturated montmorillonite, La-Mt, has been investigated. Sodium and Li as exchangeable ions have also been included for comparative purposes. XPS of La-Mt shows no migration of La(III) from interlamellar positions to octahedral sites on heating at 300°C. The water adsorbed as a multilayer on the external surface of the montmorillonite has been subtracted from the total sorbed water. Although the c-spacing of La-Mt corresponds to a two-layer hydrate, in the relative humidity range from 30 to 70%, the interlamellar water amounts to only 70% of the value for a complete monolayer. Heating at 300°C for 24 h has no influence on the uptake of molecular water between the structural layers of the La-Mt. The average numbers of water molecules per exchangeable ion sorbed into the interlamellar spacing up to 50% r.h. are: 5(Na-Mt), 3(Li-Mt) and 13(La-Mt).

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One-bodied humidity and temperature sensor having advanced linearity at low and high relative humidity range

Sensors and Actuators B Chemical ◽

10.1016/s0925-4005(01)00611-6 ◽

2001 ◽

Vol 76 (1-3) ◽

pp. 322-326 ◽

Cited By ~ 41

Author(s):

Sekwang Park ◽

Jeongho Kang ◽

Jinsu Park ◽

Suhwan Mun

Keyword(s):

Relative Humidity ◽

Temperature Sensor ◽

High Relative Humidity ◽

Relative Humidity Range ◽

Humidity Range

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Boltzmann-Based Empirical Model to Calculate Volume Loss during Spirit Ageing

Beverages ◽

10.3390/beverages5040060 ◽

2019 ◽

Vol 5 (4) ◽

pp. 60

Author(s):

Noemí del Toro del Toro ◽

Fredy Fong Casas ◽

Julio Ayan Rial ◽

Maria Caridad Portuondo González ◽

Harold Crespo Sariol ◽

...

Keyword(s):

Boltzmann Equation ◽

Relative Humidity ◽

Quercus Alba ◽

Volume Loss ◽

Air Humidity ◽

White Oak ◽

The Boltzmann Equation ◽

Relative Humidity Range ◽

Two Parameters ◽

Humidity Range

The Boltzmann equation is applied to fit data of volume loss for evaporation (in %) during spirit ageing in northern white oak (Quercus Alba) standard barrels of 205 L (+/− 10 L) using a temperature and humidity controlled cellar. The Boltzmann equation satisfactory fitted to the experimental data of the volume loss against temperature at constant humidity. Two parameters of the Boltzmann equation showed a linear dependency on the relative humidity of the air, while the other two parameters exhibited a constant value independently of the air humidity. The found empirical mathematical model can be used to calculate the volume loss for evaporation of spirits (40% v/v of ethanol) during ageing in terms of relative humidity (range: 40%–95%) and temperature (range: 10–30 °C) with significant accuracy.

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A silicon nanowire–reduced graphene oxide composite as a high-performance lithium ion battery anode material

Nanoscale ◽

10.1039/c3nr05093a ◽

2014 ◽

Vol 6 (6) ◽

pp. 3353 ◽

Cited By ~ 52

Author(s):

Jian-Guo Ren ◽

Chundong Wang ◽

Qi-Hui Wu ◽

Xiang Liu ◽

Yang Yang ◽

...

Keyword(s):

Graphene Oxide ◽

Lithium Ion Battery ◽

Reduced Graphene Oxide ◽

Anode Material ◽

High Performance ◽

Silicon Nanowire ◽

Lithium Ion ◽

Oxide Composite ◽

Reduced Graphene ◽

Battery Anode

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Bioinspired stimuli-responsive multilayer film made of silk–titanate nanocomposites

Journal of Materials Chemistry C ◽

10.1039/c7tc00149e ◽

2017 ◽

Vol 5 (16) ◽

pp. 3924-3931 ◽

Cited By ~ 26

Author(s):

Elena Colusso ◽

Giovanni Perotto ◽

Yu Wang ◽

Marco Sturaro ◽

Fiorenzo Omenetto ◽

...

Keyword(s):

Relative Humidity ◽

Multilayer Structure ◽

Multilayer Film ◽

Stimuli Responsive ◽

Term Stability ◽

Long Term Stability ◽

Relative Humidity Range ◽

Responsive Behavior ◽

Humidity Range

A bioinspired multilayer film made of a new silk–titanate nanocomposite material, showing a humidity-responsive behavior, has been fabricated. The multilayer structure mimics the structure of the cuticle of the Hoplia coerulea beetle and shows long-term stability over a very large relative humidity range.

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Entomological Problems of Food Storage in Northern Nigeria

Bulletin of Entomological Research ◽

10.1017/s0007485300030649 ◽

1952 ◽

Vol 43 (1) ◽

pp. 111-144 ◽

Cited By ~ 50

Author(s):

R. W. Howe

Keyword(s):

Relative Humidity ◽

Moisture Content ◽

Food Storage ◽

Northern Nigeria ◽

Diurnal Range ◽

Relative Humidity Range ◽

The Mean ◽

Humidity Range

In Nigeria, shelled groundnuts are stored in sacks in covered warehouses and as pyramids in the open air. At the beginning of storage the nuts comprise approximately equal quantities of whole, split and broken nuts of a moisture content of 3·4 per cent. The sacks are exposed to direct hot sun whilst stacking.The mean monthly maximum shade temperature in Kano ranges from 101°F. in April to 85°F. in January and August and the mean monthly minimum from 75°F. in May to 56°F. in January. Monthly maximum relative humidities range from 100 per cent, in August and September to 45 per cent, in February, and the monthly minimum from 71 per cent, in August to 12 per cent, in February. The range of mean relative humidity is 81 per cent, in August and 18 per cent, in February. Rains fall between April and September, 70 per cent, falling in July and August. Heavy falls are recorded on about 25 days.Inside warehouses, the maximum monthly temperatures are 102°F. in May and 79°F. in January and February, and minimum temperatures are 81°F. in June, and 58°F. in February. In August the mean relative humidity range is 93 per cent, to 70 per cent. In December it is 34 per cent. to 20 per cent.Just under the roof of a warehouse and on the surface of pyramids the diurnal range is very large.

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